CVE-2017-5159: An issue was discovered on Phoenix Contact mGuard devices that have been updated to Version 8.4.0

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CRITICAL 9.8REMOTEMITIGATE

CVE-2017-5159 is a critical-severity flaw (CVSS 9.8) affecting mguard firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered on Phoenix Contact mGuard devices that have been updated to Version 8.4.0. When updating an mGuard device to Version 8.4.0 via the update-upload facility, the update will succeed, but it will reset the password of the admin user to its default value.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.4% (top 16%)
CISA exploited list	No
Weakness	CWE-99
Published	2017-02-13
Last modified	2026-06-17

Publisher (CNA): ICS-CERT · Vendor: phoenixcontact

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2017-02-13 21:59 UTCPublished CVE record published
2026-06-17 01:20 UTCUpdated Record last modified

phoenixcontact mguard firmware MITIGATE

Affected: 8.4.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.4.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2017-5159?

mguard firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-5159 being exploited?

CVE-2017-5159 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2017-5159 affect?

CVE-2017-5159 affects mguard firmware. Severity is critical (CVSS 9.8). An issue was discovered on Phoenix Contact mGuard devices that have been updated to Version 8.4.0. When updating an mGuard device to Version 8.4.0 via the update-upload facility, the update will succeed, but it will reset the password of th

How urgent is CVE-2017-5159?

Priority 60/100. Critical severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2017-7937 MEDIUM 4.0 MITIGATE An Improper Authentication issue was discovered in Phoenix Contact GmbH mGuard firmware versions 8.3.0 to 8.4.
CVE-2017-7935 HIGH 7.5 MITIGATE A Resource Exhaustion issue was discovered in Phoenix Contact GmbH mGuard firmware versions 8.3.0 to 8.4.2
CVE-2015-3966 MEDIUM 4.0 MITIGATE The IPsec SA establishment process on Innominate mGuard devices with firmware 8.x before 8.1.7 allows remote a
CVE-2014-9193 HIGH 8.5 UPGRADE Innominate mGuard with firmware before 7.6.6 and 8.x before 8.1.4 allows remote authenticated admins to obtain
CVE-2014-2356 MEDIUM 4.3 UPGRADE Innominate mGuard before 7.6.4 and 8.x before 8.0.3 does not require authentication for snapshot downloads, wh

References

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